After the evolution of mobile telephones from an analog to a digital system, namely, transition from the first generation mobile telephone to the second, what is called the third-generation mobile telephone requires global standards that are recognized throughout the world. That is, there has been the growing need for the implementation of a third-generation mobile communications system, IMT-2000 (International Mobile Telecommunications 2000). 3GPP is a body organized to define the global standards for the third-generation mobile telephone. In the following description, the third-generation mobile telephone will be referred to as a 3GPP-compliant mobile telephone.
Let it be considered that the 3GPP-compliant mobile telephone is adopted in a compound information terminal comprised of an integrated combination of a mobile telephone unit and a GPS terminal unit. The GPS terminal unit is set for a low level sensitivity of less than −30 to −150 dBm. On the other hand, the maximum transmit power level of the 3GPP-compliant mobile telephone unit is, for example, greater than +24 dBm. It is difficult to attenuate the transmit power in the GPS terminal unit, and therefore the reception performance of the GPS terminal unit conceivably could be affected. In other words, it is presumed that the transmitter signal of the 3GPP-compliant mobile telephone unit has an effect on the GPS terminal unit when the units are arranged in mutual close proximity. Consequently, there is fear that the GPS terminal unit having a low received signal power level with a small resistance to interference may not function properly.